Annular combustor for a gas turbine

ABSTRACT

The invention relates to an annular combustor ( 13 ) for a gas turbine ( 10 ), into which combustor ( 13 ) burners ( 14, 15 ) open on an inlet side, and which combustor ( 13 ) extends in the axial direction from the inlet side to an outlet side ( 33 ) and is lined on the insides with cooled liner segments ( 16, 17 ) for protection from the hot gases.  
     In such a combustor, increased mechanical stability and flexibility in design and also simplification in manufacture and fitting are achieved by the liner segments ( 16, 17 ) being subdivided in the axial direction into a plurality of parts ( 16, 17 ) arranged one behind the other.

FIELD OF THE INVENTION

[0001] The present invention relates to the technical field of gasturbines. It relates to an annular combustor for a gas turbine accordingto the preamble of claim 1.

[0002] Such a combustor, as reproduced, for example, in FIG. 3, has beenin use in gas turbines for a long time.

DISCUSSION OF BACKGROUND

[0003] A sectional representation of an annular combustor, an “EVcombustor” (EV=environmental), according to the prior art is reproducedin FIG. 3. The combustor 26, which is part of a gas turbine (not shown)and of which only the section lying above the turbine axis isreproduced, extends in the longitudinal direction along the turbine axisin the direction of flow (from right to left in FIG. 3). On the inletside (right-hand side in FIG. 3), a number of burners 27 are distributedon a circular ring concentric to the turbine axis and in the presentcase are designed as “double-cone burners” according to EP 0321809.However, this is not absolutely necessary, and it goes without sayingthat the combustors discussed here may also be operated with otherburner variants. The swirled fuel/air mixture discharging from theburners 27 burns, while forming a flame, in the primary zone 30following the burners 27, and the hot gases produced discharge from thecombustor 26 at a combustor outlet 31 and enter the downstream turbinepart, where they expand while performing work. In order to protect thecombustor walls 29 from the hot gases, special liner segments 28 arearranged and fastened on the inside of the combustor walls 29. The linersegments 28 are designed to be continuous in the axial direction and aretherefore as long as the interior space of the combustor 26. This hasthe advantage that the number of parts and the length of the leaky gapsis minimal.

[0004] A disadvantage with the known configuration of the linerelements, however, is that the segments are comparatively long. Thiscreates problems with regard to ease of manufacture and the mechanicalintegrity. These problems become even greater and possibly cannot besolved if correspondingly large combustors having very long linersegments are required for very large gas turbines.

SUMMARY OF THE INVENTION

[0005] Accordingly, one object of the invention is to provide a novelcombustor which avoids the above-described disadvantages of knowncombustors and is characterized by simplification of manufacture andfitting and by improved mechanical stability and improved mechanical andthermal loading capacity.

[0006] The object is achieved by all the features of claim 1 in theirentirety. The essence of the invention consists in the fact that, in acombustor of the type mentioned at the beginning, the liner segments aresubdivided in the axial direction into a plurality of parts arranged onebehind the other. The individual elements become smaller due to thedivision, as a result of which their manufacture is simplified and themechanical stability is increased. At the same time, the fitting of thesegments is simplified.

[0007] In this case, it has proved to be especially favorable if theliner segments, according to a preferred configuration of the invention,are subdivided into two parts, if the liner segments are subdividedwhere the flow velocity of the hot gases is low, or if the linersegments are subdivided in such a way that the lengths of the individualsegment parts in the axial direction are approximately the same.

[0008] The fitting can be further simplified if, according to anotherconfiguration of the invention, the liner segments are fastened tosegment carriers, and the segment carriers are likewise subdivided inthe axial direction into a plurality of parts.

[0009] The liner segments are preferably convection-cooled.

[0010] In this case, the subdivided liner segments can beconvection-cooled separately, the cooling medium flowing through thoseparts of the liner segments which are situated downstream being releasedinto the hot-gas flow of the combustor.

[0011] However, it is also conceivable for transition channels to beprovided between the subdivided liner segments, through which transitionchannels the convectively cooling cooling medium can flow from, one partof the liner segments into the other part of the liner segments.

[0012] Further embodiments follow from the dependent claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] A more complete appreciation of the invention and many of theattendant advantages thereof will be readily obtained as the samebecomes better understood by reference to the following detaileddescription when considered in connection with the accompanyingdrawings, wherein:

[0014]FIG. 1 shows a section through a combustor, arranged in a gasturbine and having liner segments subdivided in the axial direction,according to a preferred exemplary embodiment of the invention;

[0015]FIG. 2 shows an enlarged detail from the representation of FIG. 1;and

[0016]FIG. 3 shows a section through an annular combustor according tothe prior art.

WAYS OF IMPLEMENTING THE INVENTION

[0017] Referring now to the drawings, wherein like reference numeralsdesignate identical or corresponding parts throughout the several views,in FIG. 1, a section through a combustor, arranged in a gas turbine andhaving liner segments subdivided in the axial direction, according to apreferred exemplary embodiment of the invention is reproduced. The gasturbine 10, of which only a part lying above the turbine axis is shown,has an outer turbine casing 11 which surrounds a plenum chamber 12 whichis filled with compressed air and in which the actual annular combustor13 is arranged. The flow occurs from right to left in FIG. 1. By theburners 14, 15, which are arranged in a head space of the combustor 13and lie one above the other in two rows, the fuel/air mixture isinjected into the primary zone 32 of the combustor 13 and burns therewhile forming flames. The hot gases produced discharge from thecombustor 13 through the combustor outlet 33 and enter the downstreamturbine. The combustor 13 is separated from the surrounding plenumchamber 12 by a plurality of segment carriers 18, . . . , 21. First andsecond liner segments 16 and 17 are fastened one behind the other in theaxial direction to the inner walls of the segment carriers 18, . . . ,21, inner liner segments (at the bottom in FIG. 1) and outer linersegments (at the top in FIG. 1) being provided in each case. The dividedliner segments 16, 17 have approximately the same (axial) length and aredivided where the associated segment carriers 19, 20 and 18, 21 meet.The location at which the divided liner segments 16, 17 meet (space 24in FIG. 2) lies where the flow velocity of the hot gases is low. Thedivided liner segments 16, 17 are convectively cooled in the same way asis already the case with the undivided liner segments.

[0018] The division of the segment carriers 18, . . . , 21 means thatthe assembly is simplified. This applies in particular to the inner(bottom) liner. If the inner liner is composed of two parts, theseparating gap can be screwed over the entire length. In this case, theseparating line of the segment carriers 18, 21 for the second linersegments 17 is accessible for screw bolts, so that a wedge is no longerrequired.

[0019] The division according to the invention of the liner segmentsenables larger combustors to be realized without correspondingly largesegments having to be constructed. In this way, recourse may be had toalready proven segment sizes. The invention also enables the sameburners 14, 15 and first liner segments 16 to be used in different gasturbines. Only the combustor outlet 33 having the second liner segments17 and their segment carriers 18, 21 is then adapted to the differentturbine inlet geometries.

[0020] The liner segments 16, 17 are thus configured as in the GT24B andGT26B type EV and SEV combustors of the known gas turbines of theapplicant (in this respect see the article by D. K. Mukherjee“State-of-the-art gas turbines—a brief update”, ABB review February,1997, pages 4-14 (1997)). A special feature is the provision oftransition channels 22, 23 (FIGS. 1 and 2) between the second linersegments 17 and the first liner segments 16. The cooling air used forthe convective cooling of the liner segments 16, 17 can flow throughthese transition channels 22, 23 from the second liner segments 17 intothe first liner segments 16 and can contribute to the cooling there. Thecooling system of the second liner segments 17 is operated with onlypart of the entire mass cooling flow in order to keep the flowvelocities low for avoiding pressure drops in the transition channels22, 23. An additional partial flow 25 is required for cooling the firstliner segments 16 (FIG. 2). The transition region between the innersecond and first liner segments 17 and 16 is shown enlarged in FIG. 2.

[0021] However, it is also conceivable to dispense with the transitionchannels 22, 23 and to design the cooling systems of the first andsecond liner segments 16, 17 separately. The cooling air from the secondliner segments 17 is then, released into the, hot-gas flow. In thiscase, the second liner segments 17 are markedly shorter and areoptimized for a minimum consumption of cooling air. The advantage of theseparate cooling lies in the fact that the transition channels 22, 23,which are complicated from the production point of view, can bedispensed with and that air is available for influencing the hot-gastemperature distribution and for cooling the gap between burner chamberand turbine. This advantage is offset by a reduced mass air flow in theburner and a small height of the cooling channels in the second linersegments 17.

[0022] Obviously, numerous modifications and variations of the presentinvention are possible in light of the above teachings. It is thereforeto be understood that within the scope of the appended claims, theinvention may be practised otherwise than as specifically describedherein.

[0023] List of Designations

[0024]10 Gas turbine

[0025]11 Outer turbine casing

[0026]12 Plenum chamber

[0027]13, 26 Combustor (annular)

[0028]14, 15, 27 Burner

[0029]16, 17 Liner segment

[0030]18, . . . , 21 Segment carrier

[0031]22, 23 Transition channels

[0032]24 Space

[0033]25 Partial flow

[0034]28 Liner segment

[0035]29 Combustor wall

[0036]30, 32 Primary zone

[0037]31, 33 Combustor outlet

What is claimed as new and desired to be sucured by Letters of Patent ofthe United States is:
 1. An annular combustor (13) for a gas turbine(10), into which combustor (13) burners (14, 15) open on an inlet side,and which combustor (13) extends in the axial direction from the inletside to an outlet side (33) and is lined on the insides with cooledliner segments (16, 17) for protection from the hot gases, characterizedin that the liner segments (16, 17) are subdivided in the axialdirection into a plurality of parts (16, 17) arranged one behind theother.
 2. The combustor as claimed in claim 1, characterized in that theliner segments (16, 17) are subdivided into two parts (16, 17).
 3. Thecombustor as claimed in claim 2, characterized in that the linersegments (16, 17) are subdivided where the flow velocity of the hotgases is low.
 4. The combustor as claimed in claim 3, characterized inthat the liner segments (16, 17) are subdivided in such a way that thelengths of the individual segment parts (16, 17) in the axial directionare approximately the same.
 5. The combustor as claimed in one of claims1 to 4, characterized in that the liner segments (16, 17) are fastenedto segment carriers (18, . . . , 21), and in that the segment carriers(18, . . . , 21) are likewise subdivided in the axial direction into aplurality of parts (18, . . . , 21).
 6. The combustor as claimed in oneof claims 1 to 5, characterized in that the liner segments (16, 17) areconvection-cooled.
 7. The combustor as claimed in claim 6, characterizedin that the subdivided liner segments (16, 17) are convection-cooledseparately.
 8. The combustor as claimed in claim 7, characterized inthat the cooling medium flowing through those parts (17) of the linersegments which are situated downstream is released into the hot-gas flowof the combustor (13).
 9. The combustor as claimed in claim 6,characterized in that transition channels (22, 23) are provided betweenthe subdivided liner segments (16, 17), through which transitionchannels (22, 23) the convectively cooling cooling medium can flow fromone part (17) of the liner segments into the other part (16) of theliner segments.
 10. The combustor as claimed in one of claims 6 to 8,characterized in that those parts (17) of the liner segments which arelocated downstream are cooled only by part of the mass flow providedoverall for the cooling of the liner segments.